As the weekend draws to a close, so to does our first taste of interleague play in the 2009 season. One of the hottest topics this side of steroids in the modern game, interleague play has strong proponents on both sides of the issue. One of, if not the, central claims of supporters is the large attendance spike reported by MLB for interleague games. In 2007, MLB claimed attendance rose over 13% historically in interleague games and over 15% in 2007. The fans want to see it, teams bring in more revenue, what's not to like?

For starters, there's MLB's deceptive attendance reporting. There are a number of issues here, so first let's start with the 2007 exclusive figures. MLB tries to make it appear that interest in interleague games is actually higher in 2007 than it has been historically. One of the points of opposition to interleague play is that it has grown stale, and the initial excitement fans showed has waned over the years. MLB is indicating here that that is not the case. The problem with that is, the season was not over when they released these figures, and so the half-season figure from 2007 was not comparable to the historical number they were comparing it too. Most of those interleague games were from June, whereas the non-interleague games were more heavily weighted with April and May games, where attendance is always significantly lower. Once the non-interleague sample picked up more summer games, the non-interleague game attendance also rose. By the season's end, that 15.4% rise in attendance in interleague games was halved to a 7.6% increase, clearly much lower than their historical rise. Other recent years all show smaller increases than the early years of interleague play. However, MLB still has their skewed midseason figures posted almost 2 years later with no mention that the figure they reported for the year at the time is not even close to accurate for the year as a whole.

That is just one of many issues with MLB's reports, however. The historical attendance figures reported by MLB are also rife with further deception. For one, most (2 out of every 3) interleague games are played on weekends (Friday through Sunday), while most non-interleague games are played on weekdays. Attendance just happens to be about 19% higher on weekends than on weekdays. The figures MLB reports assume that the only factor that affects attendance is whether the game is interleague or not. This clearly isn't the case. A game's attendance is affected by a number of other factors, including:

-where the game is being played (a game in Yankee Stadium will have a higher attendance than one at PNC Park no matter who is playing)-the day of the week-the month-whether the game is a day or night game

Of course, you could ignore these other factors if they could be expected to even out over a long enough period of time, which is generally what we do with stats when we want to measure one thing. The problem here is that none of these other factors do even out over time. MLB deliberately schedules interleague games when attendance is already likely to be higher.

For another example of the above issues not evening out, consider that because of the different number of teams in each league, AL teams have more interleague games in their parks, and NL Central teams have fewer than even other NL teams. So while the Yankees had hosted 106 interleague games through 2008, the Pirates had only hosted 86.

Something is very clearly wrong with the simplistic figures MLB gives us. None of the factors listed above that all influence attendance are accounted for in their attempt to isolate the effect of interleague play on attendance. Since MLB is not interested in giving us an accurate assessment of the effect of interleague play on attendance, we'll have to take our own look. For that, we turn, as always, to Retrosheet, where we can use gamelogs to isolate the effect of interleague play on attendance. To do this, we look at games that happened in the same park, in the same month, on the same day of the week, and either at day or night, and we compare the attendance only based on whether the game was interleague or not. So an interleague game played on a Friday night in Busch Stadium III in June is compared only to non-interleague games that also happened on a Friday night in Busch Stadium III in June. And so on for every interleague game from 1997 to 2008.

We find that attendance did rise, but only 5.9%, much less than MLB reports. We also find that the spike was higher in the early years of interleague play: in the last 5 years, attendance rose only 3.6%. So attendance does rise a bit in interleague games. Just not nearly as much as MLB tells us it does. We also can't say for certain, as we are often told, that this is a sign of greater fan interest.

Often times, the increase in attendance comes from fans of the road team that travel to support the team on the road. For example, Cardinal fans travel in hordes across the state to Kauffman and often return with stories of more red in the stadium than blue. Cub fans can easily follow their team to the new Comiskey. Does this mean they are more interested in the Cardinals playing the Royals than the Dodgers or the Cubs playing the Sox than the Mets? Not necessarily. There are plenty of reasons a Cardinal fan would go to Kansas City and not L.A. for a game, or a Cub fan would go to Comiskey but not Citi Field that have nothing to do with his or her level of interest in each game, namely that it's just easier and more realistic to get there. We can say for certain that interleague's attendance increases bring more revenue to teams (which is the other part of the argument). We can't really gauge fan interest, however, especially from such a modest spike.

Once we get past MLB's skewed presentation of the results, we can see that the majority of the increase in attendance in interleague games has absolutely nothing to do with them being interleague. What has essentially happened is that Bud Selig has observed that attendance naturally increases on certain dates throughout the year and always has, and he has somehow found a way to take credit for that. Or at least that's the way he's presenting it by so deceptively inflating the impact of his brainchild.

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comments:

interesting article. not only are the summer and weekend dates inflating the interleague numbers a bit - so are the exact weekends during which these matchups occur. for example, this past weekend was memorial day weekend. the next major holliday is fathers' day, which, believe it or not, is also home to interleague play. needless to say, people are looking to go out over these weekends, and any attendance is going to be up.

while i'm not necessarily a fan of interleague, i'm not as adamantly opposed as some. i think that interleague play does present some interesting matchups, and it does have a substantial impact in some areas. in chicago, for example, the white sox/cubs matchup has become huge here - possibly even bigger than cubs/cards for people in the area. that has created a genuine rivalry that has increased fan interest greatly, although that is probably the most extreme case of that. even in new york, i don't know if yankees/mets has eclipsed the interest of yankees/red sox, and certainly not the way it has in chicago.

i would also be curious to see how interleague attendance impacts various markets. for example, the big markets may not see much of an increase just because they have large draws regardless of the matchups, as you mentioned. some of the smaller markets, like pittsburgh, don't really have a marquee counter-league opponent to boost revenue. but places like washington/baltimore and houston/texas i could see having big impacts with their fan interest. of course, that's merely speculation, and i'd be curious to see what the numbers say regarding that.

Not a fan of inter-league play. While the Cubs and White Sox might be having a great time, what the hell do you do when Toronto hosts Atlanta as a 'natural rival' that same weekend? And with 16 National League teams and 14 American, it means a two National League teams get stuck playing each other. My biggest problem with Inter-League play is that it unbalances the schedule - with the Mets playing the Yankees six times while the Rays play the Marlins. Those teams are all competing for a spot in the playoffs, and at the end of the year they all can't say that the season was fair because we all played the same teams the same number of times. And you end up now playing 19 games against division teams - meaning one of those teams gets home advantage in the match-ups. I don't like this at all!

again, i'm not really a fan of interleague, and mostly for the unbalanced schedule issue that you mentioned, dad. one possible alternative is to have exhibition match-ups either right before or right after the all-star game and extend the all-star break. you wouldn't count the games in the schedule, but you could create a good deal of revenue with all of the "marquee" matchups.

About markets most impacted (and the impact of geographical rivalries)

I had looked at all of the geographical rivalry matchups to see what kind of difference they made. Jayson Stark had a recent article that talked about that and found that the attendance spike from interleague play went down considerably when you took out the top 4 "rivalries" (New York, L.A., Chicago, and Bay Area): I initially had a paragraph in this addressing his findings. Basically, it turned out his findings were probably entirely due to methodological error. As far as I can tell, he was using the same simplistic method as MLB uses, which doesn't account for any of the other important factors, and basically what happened was that he took out large chunks of games from 6 of the highest attendance sites and saw that the average attendance went down. Taking out all those games making the same adjustments I did in the article results in only a small change, and I think the numbers actually went up, because those sites are mostly drawing a lot of fans anyway and don't have much room to improve in interleague. However, if you take out all 10 geographic rivalries, the attendance spike does go down about half a percent or so.

I also checked taking out only the natural rivalries played in lower attendance stadia (outside the top third in attendance) to see what effect they had. I think the ones I ended up looking at were:

SF/Oak games in OaklandTex/Hou games in ArlingtonWas/Bal gamesKC/StL games in KCFla/TB gamesChA/ChN games in new ComiskeyMil/Min gamesCle/Cin games

When you take those out, the rise drops from 3.6% to just below 2.0%. Those games account for only about 13% of interleague games, so that means those handful of "rivalry" games are seeing an increase of attendance of about 14.5% (probably mostly because the road fans can travel there in large numbers more than increased interest), and everyone else sees about a 2% increase. That 2% could also be from scheduling on prime dates like holidays like you suggest, John. I didn't calculate that difference because I would have had to go before interleague play and compare what happened in previous years to get the dates to match as well, but the effect shouldn't be ignored. So it's entirely possible that non-geographic interleague games don't really make any difference in attendance at all anymore.

The teams that saw the biggest spikes in attendance in interleague play over the past 5 years:

KC (+36%)Cin (+29%)Pit (+26%)Tex, Oak, Mil (+20%)

Five of these are low attendance sites with geographical rivalries as we'd expect. Maybe Pittsburgh played the AL East a lot, who knows. Or maybe it's just an aberration because we're only talking about 36 games.

The lowest increases:

Mon (-14%, in only 9 games)Tor (-8%)Fla (-2%)Bos (0%)NYA, ChN (+2%)

These are mostly either parks that sell well anyway or have no interesting match ups. Toronto has no one to play and loses games against the Yankees and Sox. I guess no one really cares to go to Florida games no matter what.